Category Archives: Species spotlight

The Eastern Mosquitofish, Gambusia holbrooki, is one of the most widespread- and reviled- of all invasive species to inhabit Australia (Pyke, 2008). Originally introduced as a biocontrol for mosquitos in the 1920’s, it has turned out that Mosquitofish aren’t any more efficient at consuming the insect’s larvae than many other native fish (Pyke, 2008). So, in a rather familiar story to Australians (ahem, cane toads), we are now tasked with somehow managing a species listed as one of the worst invaders in the world (Pyke, 2008). To continue on this rather depressing note, there is every indication that the consequences of failing to do so are severe, as it has been associated with the decline of nine fish species, amphibians and insects (Howe et al., 1997).

When we consider the geographic range of Mosquitofish in Australia, it’s tolerance to environmental variability is clear. Less clear, however, is whether and how its impacts on native species vary with context. While some research overseas has focused on the effects of Mosquitofish density, temperature and salinity on key interactions, such as predation and competition, with native species (Alcaraz et al., 2008; Mills et al., 2004), less has been done in Australia. Ultimately, identifying the influence of context on the impact of Mosquitofish in Australian waterways will aid their management, particularly when it comes to working out the conditions at which Mosquitofish are most problematic and need to be targeted.

A common and fair assumption about invaders is that with their increasing density a higher impact on the environment occurs. However, in the context of predation, an increase in competitive interactions between invasive predators can accompany a hike in density (Pintor et al., 2009). This means that predators may spend more time interacting with each other than hunting and attacking prey. In the lab, we set out to explore the relationship between Mosquitofish density and time of day (diel cycle) on the lethal and nonlethal effects experienced by a prey, the Glass shrimp, Paratya australiensis.

In regards to lethal effects, we observed Mosquitofish to prey upon shrimp, yet the actual rate of predation did not vary between low (1 fish) and high (5 fish) fish densities, or diel cycle, which suggests that interference occurs between fish. When it came to non-lethal effects, shrimp drastically reduced the time they spent swimming (most likely to reduce their vulnerability to predation), and occupied shelters far more. The shift in these behaviors suggests that shrimp may also forage and interact less with reproductive mates in the presence of Mosquitofish, which could significantly lower their fitness. However, the shift in these activities was the same regardless of fish density and diel cycle, indicating that they were responding in proportion to the risk imposed by Mosquitofish. Interestingly, shrimp exposed to both a high density of fish and a high density of shrimp, the control, both increased their foraging activities. Ultimately, what is most notable is that even low densities of Mosquitofish have multiple negative effects on shrimp from direct consumption, causing changes in activity levels and potentially even by competing for food.

Along with density, we were also keen to look at the effect of abiotic factors on interactions between Mosquitofish and native species. One of the key mechanisms by which Mosquitofish are supposed to out-compete native species is by aggression, and their fondness for fin nipping is particularly well known (Pyke, 2008). With this in mind, we decided to look at how aggression between Mosquitofish and Australian Bass, Macquaria novemaculeata, fingerlings is influenced by a combination of temperature and salinity – two key factors in freshwater systems. Bass are stocked throughout the Eastern Drainage system as fingerlings to support recreational fishing (Cameron et al., 2012). While adults are predatory, stocked juveniles are often no larger than an adult Mosquitofish and being hatchery-bred, could be naïve to the behaviour of other fish species.

Weighing and tagging an Australian Bass fingerling

We were particularly interested in how a combination of temperature and salinity would influence aggression compared to each stressor alone. While the effect of two stressors can be the sum of both together, it can also be antagonistic (less than additive) or synergistic (greater than additive), which are much harder to predict (Sih et al., 2004). Again in the lab, we measured aggression between Mosquitofish and Bass at four different combinations of 21 °C or 28 °C temperature and 15 ppt or 35 ppt salinity. Like many fish species, both Bass and Mosquitofish were much more aggressive when exposed to 28 °C and low salinity levels of 15 ppt. Interestingly, when we combined elevated temperature with elevated salinity, 35 ppt, their aggression decreased markedly, which suggests that the effect of temperature is dependent on salinity. For both Bass and Mosquitofish, the interaction between temperature and salinity was non-additive, specifically antagonistic. This result confirms the value of considering multiple stressor effects, not just because it provides greater realism in lab experiments, but also because the outcome can be unpredictable.

Pregnant Mosquitofish tagged with an elastomer

Ultimately the impacts of Mosquitofish are complex. Our work provides no simple answers, but instead emphasises the importance of considering context, particularly in lab studies, when trying to understand the mechanisms behind this species’ success.

The very year they could be rightfully declared extinct, something was stirring in the bottom of Rexy Conallin’s bucket…..was it…..THE LAST OLIVE PERCHLET!?!

What else is hiding out there? Who is looking? How are they looking? Who is funding our ongoing need for inventory knowledge?

During one of the greatest ever bush fishing adventures of the modern era, a team of scientists, NRM people and commercial fishos from NSW, SA and Vic all got together in the Lower, lower Lachlan (Where even Clancy of the overflow was unreachable) to try out some ideas about controlling carp. This trip was the Kokoda trail of fish research expeditions and whilst all survived, none that were there will ever forget the Lachlan blues. But that is another story for later on.

1: Rex wasn’t processing the small fish catch from the fyke nets like he said he would and

2: In a small tin bucket where Rex was storing the catch for “later” lurked a different looking fish.
Cam’s sharp eyes had picked out the first olive perchlet (Ambassis agassizi) caught in the Lachlan River for nearly fifty years, commonly considered the threshold for declaring something extinct. Like Plato once stated, “where there’s one olive perchlet, there must be at least two more olive perchlets” (although the Bible’s Genesis seems to disagree with this conclusion assuming Adam and Eve were not Tasmanian).

A catch of perchlet and the net from whence they were re-discovered in the Mountain Creek outlet channel, lower, lower, Lachlan. Note Rexie’s carp cage at the right.

A follow up survey revealed a massively abundant population of olive perchlet through the local waterways with the species completely dominating the catch in many nets (3000+ individuals per fyke) and co-existing happily in shallow, isolated pools with yellowbelly, carp, redfin, gudgeons and smelt…….

…….And cute little turtles…………

…………..And this freak of a hardyhead (top one) with no face whatsoever!!!

Indeed this was the only known population of olive perchlet in the entire Murray Catchment. And it was going OFF! What was unique about this place that the olive perchlet should be here and why didn’t we know they were there? The habitat where they were first found is at the bottom end of a puny little channel with in-stream barriers galore, poor water quality and every now and then State Water would unleash a Biblical flood of pelican crap infested green water that would shake the very leaves off the redgums downstream through that channel. “These fish should be flourishing in the Murray”. But on reflection, the key things that seemed to be there for these perchlet was a combination of low flow habitats and instream macrophyte beds like this……

At the bottom of the Lachlan, most irrigation flows don’t arrive, increasingly since more water has become diverted up Willandra Creek rather than the bottom of the main channel. So the drought processes that would have occurred regularly in these Murray River catchments, that is summer low flows and regular flow variability to maintain macrophyte bed growth and diversity. In fact, a large part of the population existed within an area that was between where we drain the summer flows off to fill lake Brewster and where we smash them back in via the Mountain Creek outlet. In addition, the water takes so long to get down the Lachlan from the upper catchments (where it rains) that water arrives warm and there is no big mass of water moving through to other places (Lachlan water stays in the Lachlan!). So they may have an ideal little refuge where they are sheltered from the regular reversals of hydrology and water quality that predominate throughout their former range.

How to design a perchlet refuge. Original artist’s rendition of the purpose built perchlet refuge.
As scientists what are want to do, we pulled some of the perchlets heads apart, ethically, to look at their otoliths – ear bones that record their growth like the rings of a tree. Low and behold, these fish were all from a single year class that seemed to link back to a pulsed flow event during spring that year, But No; otolith aging revealed that the spawning STOPPED once the flow pulse hit. All of the fish were in fact spawned in the period preceding the flow pulse at the exact point that water temperature reached 23 degrees C and stopped once the flow pulse dropped the temperature again. This is EXACTLY the temperature that Angela Arthington and …ahh….Milton said they would spawn at in Queensland during the eighties (Milton and Arthington 1985). So there we have it, water temperature, low flow habitat and macrophyte beds, all combined with a unique little refuge from many of the impacts of the water regulation going on all around and you can still have olive perchlet.

The spawning period of olive perchlet in relation to water temperature of the Lachlan River (McNeil et al. 2008).

So there ARE hidden little gems out there! The last remaining bastions of a Murray that was, unique linkages to our past, heritage places and conservation hot-spots. But serendipity does not come to those who stay at home playing the x-box or indeed writing conservation and recovery plans in Canberra or those that effectively manage budgets to protect asssets identified using risk assessment methodologies supported by baysian belief networks and decision support models. Or even those, it appears, that run national monitoring programs designed to monitor the population structure of fish in the Murray-Darling Basin.

In fact all past monitoring had missed this population completely, could this be happening elsewhere? Could there be other populations of perchlet lurking, waiting, could there be other species? Purple spotted gudgeons? Murray hardyhead? Pigmy perch? Purple helmeted pocket gudgeons? OK, Tarmo Raadik made that last one up, but you see the point?

The answer is yes. Mike Hammer a while back woke up in the middle of the night after a vivid dream, muttered, “I know where they are” and slipped out of bed and off to the Murray where he found a robust little population of purple spotted gudgeon waiting for him, calling him. Again, the only one in the Murray catchment. The yarra pigmy perch called out to him on another moonlight night and somnambulated down to the Barrages to discover populations down there. But its never big government programs that find these guys, and why not? I personaly believe that two things are driving this problem

1: A focus on big fish for conservation and community and

2: A love of electrofishing in big rivers as a fish monitoring strategy.

After the discovery of the olive perchlet we asked, How did we miss these guys and are we missing them everywhere we monitor? So we ran a whole heap of SRA (Sustainable Rivers Audit) samples through the known population. We caught olive perchlet, but not many and we know from the netting they were thick in the water. But the SRA and similar monitoring programs want to catch big fish and so they do. Bony bloody herring, carp but importantly golden and silver perch and Murray cod – EPBC listed GODS of fish. Common as bloody muck. But are the perchlet EPBC listed? Are Galaxias rostratus EPBC listed? Are southern pigmy perch EPBC listed? Are the Southern Purple spotted gudgeon listed?

No, its just big fish and a heap of species that have been naturaly locked into tiny little ranges for thousands of years due to their natural inability to cope with the world around them. I reckon half the big fish are listed because people use the wrong bait. But hands up who has caught a shitload of Galaxias rostratus lately? The silence is deafening. And here is the real problem, there is NO focus on studying, listing and planning for the restoration of small bodied, wetland oriented fish, unless you are already a useless species at the end of your natural shot at the evolutionary title (I’m looking at YOU Mogurnda clivicola). The water industry delivers flows for inundating wetlands with little to no strategies for how their flows are targeting and tailored towards the recovery and sustainance of these wetland fish species. We raised these concerns a decade ago (see Closs et al. 2005) and since that time the little rare species have just about disappeared from floodplains across The Murray catchment. Are they headed for the olive perchlet and purple spotted gudgeon world of “oh, when did they dissappear? I wasn’t watching!”

NO, we Must look for these populations using appropriate methods and targeting the appropriate habitats. We need to monitor the Killawarra Floodplain on the Ovens, We need to monitor the Werai Forest on the Edward/Wakool, and the olive perchlet have taught us that we need to monitor that crappy little outlet channel at Lake Brewster, the purple spotted gudgeon has taught us that we need to monitor those crappy little wetlands that run through caravan parks on the Murray and mostly we need to monitor that little patch where no one has looked and where the next exciting discovery is waiting to help us bring back the fish to the Murray catchment.

THEYRE OUT THERE PEOPLE!

Help cheer up Janice Kerr’s little Oliver perchlett, find him some friends, find and revive the small fish! (original artwork by Janice Kerr).

Editor’s note: Thanks Dale for an insightful and inspiring article. It would be really interesting to hear the thoughts of other fish survey folk on related issues, maybe via some brief comments/letters………

The Common Carp (Cyprinus carpio) is regarded as one of the most invasive species in the world (Lowe et al. 2000), not only because of its destructive feeding habits, but its resilience in a variety of environments, and highly fecund reproductive nature. In addition to competing with native fish species for food and space (Brumley 1991, Diggle et al. 2012, Fletcher et al. 1985, Koehn et al. 2000), carp are also responsible for habitat degradation and the increasing turbidity in the waters they inhabit (Koehn et al. 2000). The first records of carp introductions in Australia occurred in 1859 and 1865, where carp were released into ponds in Victoria and New South Wales, respectively (Koehn et al. 2000). However, these fish were isolated to these water bodies, and it wasn’t till the 1900s when carp were released into the wild (Koehn et al. 2000). The spread of carp remained fairly limited until carp were introduced into the Murray River in Victoria in 1964, where they proceeded to disperse throughout the Murray-Darling Basin (Koehn et al. 2000). The spread was further assisted by widespread flooding in the early 1970s, as well as the translocation of fish to new localities (Koehn et al. 2000). Carp are now established in every state in Australia bar the Northern Territory, including isolated populations in Western Australia and Tasmania (Koehn et al. 2000). It is the population in Tasmania which continues to push the biological boundaries of this species, where carp continue to survive despite the relentless efforts of the Tasmanian Carp Management Program, and the extreme climates associated with their location.

Picture 1. A group of carp huddling close together for protection, this photo also features a close relative the goldfish, which is often the culprit of numerous carp sighting reports to the Inland Fisheries Service each year.

The biology of the common carp is what makes them so destructive, and once established in a particular water, makes the task of eradication difficult and in many cases impossible. The biology is summarised clearly by Koehn et al. (2000), which states that carp have broad environmental tolerances and thrive in habitats that have been disturbed by human activities. Although carp can grow to weigh 60 kg and 1200 mm in length (Brumley 1996), fish in the 50 gram to 5 kg range are more commonly seen (Koehn et al. 2000). Female carp mature between 2-4 years of age and can produce over a million eggs each year (Koehn et al. 2000). This estimate in egg production is largely dependent on the body size/maturity of the fish. They may also spawn several times in a year if conditions are adequate. The carp’s ability to grow quickly to a large size, and feed at low levels of the food chain suggests that they may prevent the transfer of energy and nutrients to populations of other large fish (Koehn et al. 2000). In particular, Carp feed by filter feeding small particles from either the water column or sediment, and it is this behavior that results in the stirring up of fine sediments and increasing turbidity (Koehn et al. 2000). When you take all these factors into account, you can see why the carp is regarded as one of the most invasive species in the world!

Picture 2. Spawning carp in the warm shallows

The majority of carp research in Australia has been focused on the Murray-Darling Basin, however, the Tasmanian model is unique in that the carp are now isolated to a single lake located in the central highlands, where the chance of complete carp eradication for the State is still a reality. Carp were discovered in Tasmania in the interconnected lakes Crescent and Sorell in 1995 (Diggle et al.2004, Donkers et al.2012). This occurred on the 28th January 1995, when an angler found the remains of a fish that was being eaten by a sea eagle (Diggle et al. 2012). After confirming that the fish was a carp, the IFS undertook back-pack electrofishing surveys on the 1st February, which confirmed that carp were present in Lake Crescent (Diggle et al. 2012). The outflow from Lake Crescent was closed and downstream surveys began immediately. Lake Crescent was closed to the public on the 18th February (Diggle et al. 2012). The outlet structure at Lake Crescent was fitted with an internal 1 mm meshed screen and the outflow was reopened on the 24th February to supply water for downstream domestic and stock use (Diggle et al. 2012).

Picture 3. Legislation enabled Lake Crescent to be closed to the public soon after carp were discovered

The discovery of carp raised immediate alarm and concern in the Tasmanian community at large, including state agencies, anglers, environmentalists, and farmers (Diggle et al. 2012). Initially a carp task force was formed, which later evolved into a working group with expert representatives (Diggle et al. 2012). The task force identified the following objectives:

1. Contain carp to the lakes Sorell/Crescent catchment

2. Develop a water management plan that provides for and protects the water supplies for Bothwell, Hamilton and irrigators to achieve objective 1 and assist with 3 and 4 below

3. Reduce the existing carp population

4. Eradication of carp

5. Prevent introduction to new water bodies and the reintroduction to cleared waters from both inter and intra state sources

6. Undertake legislative and communication strategies to minimise damage to tourism, while facilitating the above objectives.

Physical removal was deemed the best option and involved using an integrated fish down approach. This included the use of electrofishing (back-pack and boat), net fishing (gill and seine nets), traps (steel and fyke nets), and tracker fish (carp surgically implanted with radio transmitters) (Macdonald and Wisniewski 2011, Walker and Donkers 2011). Further recruitment was also prevented by deploying a combination of wire mesh and purpose built polyethylene barrier nets to block carp from their preferred spawning habitats (Diggle et al. 2012, Taylor et al. 2012). After maintaining vigilant fishing effort for many years, the last wild carp was removed from Lake Crescent in December 2007 (Donkers et al. 2012).

Picture 4. A haul of carp captured from Lake Crescent using a seine net

Since then sampling surveys have been undertaken each year to confirm the eradication of carp from Lake Crescent, and for the last 8 years there has not been any presence of carp. The eradication of carp from Lake Crescent has now allowed increased effort and resources to be focussed on Lake Sorell, using the same techniques proven in Lake Crescent but modifying them when required in order to improve efficiency.

Carp eradication in Lake Sorell posed a lot more issues than Lake Crescent due to its larger size and diverse habitat (rocky shores, deep reef structures, and large expanses of marshes). Carp numbers were relatively low in Lake Sorell until a large recruitment event in 2009, where juvenile carp were detected at various marshes around the lake (Inland Fisheries Service 2010). Rotenone was used to kill over 14 000 fish in the 6 weeks after the discovery, however it was estimated that approximately 50 000 fish were recruited in this event (Inland Fisheries Service 2010, 2012). Over the next 6 years the proven techniques and strategies used in Lake Crescent were used to remove as many carp as possible from Lake Sorell. Some of these strategies evolved but the principles still remained the same; to prevent spawning and to continue to catch as many carp as possible each year.

Picture 5. Juvenile carp aggregating in the warm shallows made targeting them with gill nets very efficient

The focus of the majority of the fishing effort remained on the carp from the 2009 cohort, however, small numbers of larger individuals caught from previous cohorts were still popping up each year (Inland Fisheries Service 2011, 2012, 2015). A mark-recapture population study was implemented in January 2012 in order to try and get a better grip on how many carp were actually left in the lake (Inland Fisheries Service 2012). This method was based on a similar study undertaken in Lake Crescent over the 1998-99 season, which yielded very accurate results (Donkers et al. 2012, Inland Fisheries Service 2012). A total of 803 juvenile carp from the 2009 cohort were captured, tagged, and released back into the lake (Inland Fisheries Service 2012).

Picture 6. One of the carp tagged as part of the mark-recapture population estimate.

Following the release of the carp, running estimates of the remaining carp population were able to be calculated based on the recapture ratios of tagged to un-tagged carp. Not only was this handy for the IFS to know when reporting back to stakeholder groups, but it was also beneficial towards the morale and drive of the Carp Management Program. The estimated number of fish remaining demonstrated that a real impact on the population was being made, and the goal of eradication was getting closer.

Although the peak carp season is defined as the months between October and February (peak water temperatures in conjunction with rising lake levels), fishing effort continues in the cooler months. Koehn et al. (2000) states that carp can adapt to water temperatures as low as 2oC and as high as 35oC. The carp’s ability to survive in such a broad range of temperatures is nothing short of amazing, and to witness carp being caught in such low temperatures is testament to their resilience. The Central Highlands of Tasmania is known for its inclement wild weather, and although it limits their growth, it fails to stop the mighty carp. Although the carp become significantly less active in colder weather, they still continue to move around the lake when conditions are suitable. Historically, transmitter fish were seen to congregatein just two marginally deeper locations of Lake Sorell in winter (Inland Fisheries Service 2014, Taylor et al. 2012). It is likely that the deeper water in these areas has a stable and warmer overall temperature, as it is less influenced by external environmental factors, thus the carp move to these areas to seek warmth. Although some carp have been caught as a result of these winter aggregations, the last few winters have proven difficult, as the fish have been widely dispersed around the lake due to high lake levels.

Picture 7. A cold, still morning at the IFS Lake Crescent Field Station.

Picture 8 (a & b). There aren’t many places around Australia where carp management activities occur in this sort of weather!

Picture 9. It makes it hard to catch carp when shards of ice are tangled up in the gillnet!

Picture 10. Despite the water temperature dropping to 2.4oC with the surface of the water frozen solid, these carp were still kicking around when removed from this holding pen.

Picture 11 (a & b). A catch of spring carp in cold, snowy conditions

Is it possible to eradicate carp from Lake Sorell, you may ask? The last 2014/15 financial year resulted in 1254 carp caught, which brings the total number of carp removed from Lake Sorell to 40 135 since their discovery in 1995 (Inland Fisheries Service 2015).Locating and targeting fish is becoming increasingly difficult. Consistent and high levels of gill net effort have been identified as the fundamental technique for not only fishing the population down, but also reducing the risk of spawning. As many as 13 gill nets, measuring anywhere from 100 to 750m each, were set and retrieved each day during the peak fishing period from October to February (Inland Fisheries Service 2015). The majority of these nets were set over night. Despite drastically increasing the fishing pressure by 30 times in the last two seasons, the total carp catch and catch per unit effort (CPUE) continued to decline (Inland Fisheries Service 2015).

Therefore it was recently decided to review the population estimate generated from the mark recapture survey, given the low catch rates despite increased fishing effort. The new estimate accounted for both natural mortality, and various scenarios of tag-induced mortality (Inland Fisheries Service 2015). By taking these factors into account, it was estimated that the remaining population size of carp in Lake Sorell as of July 2015 could range from 2078 to 3603 fish. This is strongly influenced by the percentage of tagging mortality considered (Inland Fisheries Service 2015). Active fishing continues to remove the larger fish from the population limiting the number of fish reaching maturity. It is envisaged that by the end of the 2017/18 season, the Carp Management Program will eradicate carp from Lake Sorell…Then, whats next? Redfin Perch? Tench? Goldfish? foxes..?!

Picture 12. Electrofishing a small aggregation of carp in the shallows over the 2014/15 summer

For more information on the trials and tribulations of the Tasmanian Carp Management Program, please contact Jonah Yick at [email protected].

The Inland Fisheries Service Website includes links to many of the publications cited in this article:

Diggle J, Day J, and Bax N (2004) Eradicating European carp from Tasmania and implications for national European carp eradication. Fisheries Research and Development Corporation Final Project Report (Project No. 2000/182), Canberra.

Lowe S, Browne M, Boudjelas S and De Poorter M (2000) 100 of the World’s Worst Invasive Alien Species A selection from the Global Invasive Species Database. The Invasive Species Specialist Group (ISSG). International Union for Conservation of Nature.

Macdonald A and Wisniewski C (2011) The use of biotelemtry in controlling the common carp (Cyprinus carpio) in lakes Crescent and Sorell. Technical Report No. 1. Inland Fisheries Service, Hobart.

Taylor AH, Tracey SR, Hartmann K, and Patil JG (2012) Exploiting seasonal habitat use of the common carp, Cyprinus carpio, in a lacustrine system for management and eradication. Marine and Freshwater Research. 63(7): 587-597.

Walker R and Donkers P (2011) An examination of the selectivity of fishing equipment in relation to controlling the common carp (Cyprinus carpio) in Lakes Crescent and Sorell. Technical Report No. 2. Inland Fisheries Service, Hobart.

Editor’s note: This is a thoroughly prepared article based on an impressive applied research and management commitment that is supported by outstanding photographs. A massive thank you to Jonah for contributing this article.

The Murray Hardyhead (Cratercephalus fluviatilis) (McCulloch 1913) is a small freshwater fish endemic to the Murray Darling Basin. Due to numerous threats the Murray hardyhead have suffered a decline in distribution on both a state and basin wide scale (Ebner et al. 2003; Hammer et al. 2009; Ellis et al. 2013). Murray hardyhead have not been recorded in New South Wales for the last decade and may be extinct in the state (Ellis et al. 2013). Currently there are eight known sites within South Australia and Victoria where viable populations of Murray hardyhead exist (Ellis et al. 2013). The species in considered to be of conservation significance. It is listed as Endangered under the EPBC Act and Endangered under the International Union for the Conservation of Nature Red List, threatened under the Victorian Flora and Fauna Guarantee Act, and critically endangered in South Australia (Ellis et al. 2013).

Disher Creek and Berri Evaporation Basin form part of Murray River wetland systems used for saline water disposal near Berri, in the Riverland region of South Australia (Suitor 2009; Suitor 2012). Sampling efforts of Murray hardyhead at these sites has seen a steady continuous increase in relative abundance since the millennium drought (Suitor 2014; Wegener et al. 2015). Monitoring of both Riverland populations of Murray hardyhead in February 2015 identified strong abundances, which are likely to reflect a positive response to on ground habitat conservation efforts by the Department of Environment Water and Natural Resources, using water supplied by the Commonwealth Environmental Water Office.

This promising monitoring result presented an ideal opportunity for collection of a sub-population of Murray hardyhead from these sites to relocate into an appropriately prepared wetland in Victoria. This interstate translocation was implemented as an action under the National Murray hardyhead recovery Plan (Stoessel et al. 2014)

To the best of our knowledge this is the first official interstate translocation of threatened fish between South Australia and Victoria. The Murray hardyhead Recovery Team, is at the centre of a well-established collaborative network formed during a decade of conservation programs which enabled this cross-border translocation process to be completed in a matter of weeks.

I approached the task of finding an Honours research topic and potential supervisors with trepidation; however, upon setting foot in the office of the Freshwater Fish Group, all nerves and fears were put aside. My supervisors for the research project, Dr Stephen Beatty, Dr David Morgan, and Dr Brad Pusey were everything one could hope for, supportive, informative, and always approached tasks with a good sense of humour. It also helps that two out of three were Freo supporters like myself.

Me sampling for salamanderfish in a roadside pool south of Northcliffe Western Australia (Photo: Stephanie Mugliston)

My Honours research aimed to determine how climate change has impacted on the aestivating fishes of the south-west of Western Australia, and how it would continue to do so into the future. One of my model species, the salamanderfish, soon became my favourite. I will never forget the excitement of pulling up a seine net and finding a salamanderfish for the first time. The salamanderfish itself may not be the most beautiful and brightly coloured freshwater fish, but if there is anything I have learned by studying it, it is just as fascinating as any other freshwater fish out there. From surviving in ephemeral acidic wetlands (pH of 3 – more acidic than wine!), to its ability to aestivate, its unique morphology (including its bizarre neck-bending ability), and its phylogenetic placement, the mystery of this species only deepens.

Typical salamanderfish habitat during the wet (top) and dry (bottom) seasons – displaying the ephemeral nature of the wetland

I was soon hooked and hoped to find more salamanderfish with each successive drag of the seine net. Unfortunately this was not always the case and one pull of the seine net turned into six, before moving on to the next wetland. My results painted a rather bleak view for the outlook of the enigmatic species, with large range reductions observed, predictor variables for presence directly linked to climate, and global climate models predicting a further drying within the region. I am hopeful however, that the findings from my research will allow for better management strategies to be implemented, as it would be a real shame if this fish was not around for future generations to admire and work with, like I have had the privilege.

Three female salamanderfish in a holding bucket prior to being measured

Not the most colourful or rare of north Queensland’s suite of amphidromous cling gobies but I do have a soft spot for the ‘Sicky’. The rabbit-headed cling goby (Sicyopterus lagocephalus) is a relatively large representative of the cling goby group found in the Wet Tropics of north Queensland and other places around the Pacific. It is relatively abundant in streams of the Wet Tropics and is a sucker for extreme high flow environments.

This species was the star of the show from a few years back when I was looking at flow performance in a bunch of sympatric Gobioids for my honours research. Amongst other things, this involved documenting microhabitat preferences for each species in terms of flow velocity, substratum composition, depth etc. During flume tank trials they could not be moved, even with the motor maxed out and producing flows of over 1.4 ms-1. The key to this ability is a suction cup-like appendage formed from their two fused pelvic fins [a trait common to all gobies but refined in many Sicydiine species (see Maie et al., 2012)].

A male ‘Sicky’ in wet season attire; typically when they are looking their best.

This neat attribute also allows them to colonise novel habitats that very few other fishes can access (e.g. chutes, above waterfalls), giving them the key to a huge diversity of habitats across a range of elevational and flow velocity gradients. However, it never ceases to amaze me just how specific this species is with its habitat preferences. In fact, the habitat selection of this species is akin to obnoxious Queenslanders watching a state of origin match and carrying on if the referee doesn’t award every penalty in their favour– very predictable.

This predictability (of Sickys) means you can turn up to a site, scout around for their preferred habitat, put a mask and snorkel on, and more often than not, stick your head in the water to find them going about their business. I’ll never forget the first time I went to Emmagen Creek with Ebb and he pointed to a fast flowing run and told me I would find a ‘Sicky’ in the midst of it. Sure enough, there was a large, brightly coloured male goby parading around in front of me in water that I could hardly hold position in.

Editors note: Despite working with the guy and being aware of his hatred for Queensland Origin success, I have decided this article should still be uploaded to the Lair.

It was late September in the alpine reaches of Victoria. The air temperature was a brisk 13ᵒC, worse still, the stream water temperature was around 8ᵒC. Looking around at my trusty team, they stared shivering, dazed, and with some horror, at one of three streams I expected them to get into over the next three days in search of barred galaxias nest sites! Despite the hesitation, over the next three days the team found a total of 13 nests, which was pretty amazing considering only two had ever been previously located.

The species under question, barred galaxias, is a threatened native fish which grows to around 160 mm in length. The species is now restricted to only a handful of isolated sites in headwater streams of the Goulburn River system in Victoria. Knowledge of barred galaxias ecology is pretty sketchy. This study has helped to fill the information void by documenting details of nest sites, incubation and hatching of eggs, as well as the raising of larvae.

Barred galaxias egg cluster, Luke Creek (photographer: Joanne Kearns)

We confirmed that spawning of the species occurred from late winter to early spring in riffles immediately upstream of pools (Stoessel et al. 2015). Interestingly, there was also a suggestion that female barred galaxias deposited eggs at a number of sites rather than a single site (Stoessel et al. 2015), a behaviour which has only ever been documented for one other galaxiid, the flat-headed galaxias Galaxias rostratus (Llewellyn 1971). On return to the lab, eggs placed into incubators took a maximum of 48 days to hatch, and newly hatched larvae were approximately 9 mm in length (Stoessel et al. 2015).

Barred galaxias monitoring (photographer: Renae Ayres)

Knowledge gained of the species reproductive ecology, was used to breed several hundred barred galaxias, which, in addition to those hatched from the wild, were used to bolster parent populations badly affected by the devastating Black Saturday bushfires, and also to establish a small number of translocated populations. The success of the project is a real credit to the science employed, and in particular the team. For further information regarding the study, refer to: http://openjournals.library.usyd.edu.au/index.php/LIN/article/view/8635

Barred galaxias on net (photographer: Joanne Kearns)

References

Llewellyn, L.C. (1971). Breeding studies on the freshwater forage fish of the Murray-Darling River system. The Fisherman 3, 1–12.

Wayne Koster, Dave Dawson and Tarmo Raadik from the Arthur Rylah Institute have recently undertaken a project to locate the threatened Australian Whitebait (Lovettia sealii) in the lower Tarwin River, South Gippsland, Victoria.

The species was thought to exist only in Tasmania, however, a population was discovered in 1993 on mainland Australia in the Tarwin River. This is the only known location on mainland Australia where the species is found.

Surveys using fine mesh fyke nets between August and October 2014 confirmed the species is still present in the Tarwin River system, with small numbers of fish collected in September migrating from Anderson Inlet to the upper reaches of the Tarwin River estuary to spawn. The current project aims to gather population data and identify key spawning habitats so that they can be protected.

Listed as Critically Endangered in Victoria, little is known about this tiny fish, which only lives for one year. The project is funded by the Victorian Environmental Partnerships Program, which addresses critical risks to threatened species and native vegetation throughout the state.

Running freshwater has and always will be a novelty for me. I am originally from the mallee country of northern Eyre Peninsula (near Warramboo, South Australia), a region which contains no permanent freshwater above ground (and very little below it). The name Warramboo is from the local Nauo aboriginal language and means ‘place of water’, but this refers to ephemeral samphire swamps and not to any drinkable water. The Great Australian Bight is nearby and I regularly went swimming or fishing in the salt, however the absence of freshwater gave it a strange appeal.

I moved to North Queensland some 2 ½ years ago to further my education in the realm of fish biology at JCU. It wasn’t long before I experienced the first of many fishing trips to the rivers of both the wet and dry tropics, beginning with the Herbert River. I didn’t know the local fish fauna very well, but soon discovered the Herbert to be full of ‘sooties’, ‘junglies’, ‘poons’ and ‘barra’.

Following several successful trips to the Herbert, I got my first real experience of the wet tropics in Tully Gorge. Fishing the Tully by foot is not at all like fishing the Herbert or Burdekin rivers, and I was informed before we set out that stumbling, falling over and getting wet up to my shoulders was par-for-the-course at this locality. This was certainly the case as casting a fly-line required wading in waist-deep in order to reach the far bank, where all the fish are located. All this proved to be worth it though as, up in the Gorge section, the Tully is an extremely healthy ecosystem, despite the altered flow from the hydro plant, and is chockas full of fish. I was told that the Tully contains two types of sooty: the regular ‘sooty’ (Hephaestus fuliginosus) that is distributed throughout much of north-eastern Australia’s tropical rivers, and the ‘Tully sooty’ (H. tulliensis). After casting the fly to a few likely looking locations, I hooked and landed the first of several of these enigmatic fish. The difference between the two closely related species of sooty became immediately apparent when seen up close: the Tully sooty has a sharper snout, relatively smaller mouth-gape, sightly darker colour, more prominent dorsal and pectoral fins and a dark, red eye.

Of the 24 recognised species of Terapontids (grunters) in the rivers of Australia, the Tully sooty is unique in being endemic to the wet tropics of north Queensland (Allen et al., 2002). The major rivers of the wet tropics are clear and fast flowing for much of the year, and the Tully sooty is adapted to these conditions by being an exceptionally strong swimmer (personal obs.). Despite their limited range, they are extremely abundant and being one of the larger fish species of the wet tropics, they are one of the first species observed when snorkelling (where it is safe to do so). They regularly form schools with the closely related ‘sooty’ where the range overlaps (personal obs.) and while I have been able to immediately tell the difference between the two species, it is possible that a hybrid of these two exists in some regions (Pusey et al., 1995). Adding to the mystery here, a recently completed genetic study found that H. tulliensis groups more closely with species in the genera Syncomistes and Scortum than with others in the ascribed genus Hephaestus (Davis et al., 2014). Another characteristic I have noticed that may be used to distinguish the two species is the prominence of dorsal spines in H. tulliensis (the webbing between spines on the anterior dorsal fin extends between the tips of fins in H. fuliginosus, but takes more of a serrated appearance in H. tulliensis) (personal obs.).

Fig 2 – Juvenile Tully sooty (Russell River), approx. length = 80 mm

Other distinguishing characteristics of this species, are the mottled body colourations (seen only in certain individuals and differing from river to river) (Pusey et al., 2004; personal obs.) and an unusual condition where the lips protrude from the mouth and exhibit a fleshy, blubbery (hypertrophied) condition (correlated with dietary shifts in H. fuliginosus) (Pusey et al., 1995).

I should state here that I am not actively researching the Tully sooty: my PhD focusses on the effects of hypoxia and temperature on physiological responses in genetically-distinct populations of barramundi (Collins et al., 2013). Growing to over a metre in length, and having significant commercial value (as well as being great to eat) barra have attained an iconic status in tropical Australia. This species displays habitat affinity with the natal river (not quite as strong as Pacific salmonids) and is distributed from Onslow (WA) to Maryborough (QLD). Environmental conditions (temperature and dissolved O2) vary enormously across the species’ distribution (Butler & Burrows, 2007 ; Walker et al., 1984), and while genetic differences between populations have been well established (Jerry et al., 2013), it remains unclear just how phenotypically and physiologically different the populations are.

Barra occupy most of my 9-to-5 time, but I still enjoy investigating my favourite Aussie freshwater native in its natural environment (which just happens to be some of the most stunning country in all Australia). While significant progress has been made in understanding the physiology and environmental tolerance of barra, similar information is lacking for not only the Tully sooty, but for many other species endemic to the wet tropics and provides scope for future research.

I guess like most fish researchers, I have several ‘favourite fish’, so when asked to nominate a favourite terapontid grunter, I had to put some thought into it. I love watching Coal grunter (Hephaestus carbo) in their natural habitat, they’re a stunning fish found in beautiful environments, and at the risk of anthropomorphism, have genuine personality (being totally unafraid of swimming up and giving the clumsy two-legged intruders into their habitats a thorough checking-over). But my favourite terapontid would probably be something a bit different, the Small-headed grunter, Scortum parviceps. Endemic to the Burdekin River catchment, I’ve found them a somewhat elusive fish. My first real encounter with them took place in the very early stages of my PhD, when my supervisor (Brad Pusey) suggested if I needed some specimens for dietary and morphometric analysis, that my best bet would be the upper Burdekin catchment, at the same time warning me they could be a bit ‘hit and miss’ to find. I was soon at Reedy Brook station (my father in tow as a field assistant) in the picturesque basalt country of the upper Burdekin River, trying to describe to the somewhat bemused grazier the specific fish I was after (most people head up there to catch Sooty grunter, Hephaestus fuliginosus). Then he stated ‘Ah, I know what you mean, you want some ‘Fat-guts’. I know a spot where we get them, but they taste like sh&t.’ (if they taste anything like their congener S. ogilbyi, this is a fair assessment).

An hour or so later (after some navigational issues) we were at a beautiful, essentially untouched lagoon nestled against a hill side, setting up camp. I soon caught my first Fat gut on a strip of meat (despite subsisting mainly on plants, they do opportunistically take animal prey), and once in hand saw the reason for the grazier’s description. They’re built like footballs, almost as wide as they are long (being a specialised herbivore they have a characteristically long intestine, giving them their local ‘fat-gut’ moniker), and are a surprisingly powerful fish on a fishing line, especially larger models pushing 400 mm total length (a couple busted off my father’s line, which was pointed out as obviously due to his poor knot-tying abilities). I’d strung up a gillnet and within a ½ hour had 25 fish on ice, so my first field collection was off to a flyer. I’m not even sure why I like this fish so much, but their contrast to the closely related sooty grunter piqued my interest in evolutionary drivers of morphological diversification straight away (which then became a central theme of my PhD). Some of the appeal may be the beautiful country I chased them in (with the ‘old man’, which is always nice), or the fact this initial success gave me much needed confidence at the early stages of the PhD (when you really do wonder if you’re making the right move). I caught quite few more Fat-guts over the next few years, but never with so much success. Being a specialised herbivore (quite rare for Australian fish), they became one of the stars of my research.

About me: I’m not even sure how to describe myself professionally (some of my colleagues joke about my professional identity crisis). My ‘real’ job (that pays the bills) deals mainly with water quality in the Great Barrier Reef, which is interesting, challenging and rewarding in the sense of feeling you can make a difference. Fish are almost a sideline hobby, but something I enjoy immensely (its nice, but uncommon, when these two threads meet), although, my favourite fish evolutionary research topics admittedly don’t have much of an applied basis. I guess I could be classified broadly as a freshwater ecologist, dabbling across water quality, fish, even ‘bugs’ (macroinvertebrates). I actually started out as a bug person, spent a few years staring down a microscope, saw the light, got into fish diet, and then proceeded to spend 5 years staring down microscopes at the bugs fish ate (though the macroinvertebrate ID skills I gained were probably the best grounding I could have had for my PhD in hindsight).

Photo: One of my first ‘Fat-guts’. The picture doesn’t really give justice as to how ‘broad across the beam’ these fish are.

Editor’s note: Dr Aaron Davis does not act like a doctor, in the nose-up kind of way at least. But gee he publishes some great research papers on the grunters. http://research.jcu.edu.au/research/tropwater/resources/aaron-davis